AmrZ regulates cellulose production in P seudomonas syringae pv. tomato DC 3000

• Published in: Molecular microbiology 2016-03, Vol.99 (5), p.960-977
• Main Authors: Prada‐Ramírez, Harold A., Pérez‐Mendoza, Daniel, Felipe, Antonia, Martínez‐Granero, Francisco, Rivilla, Rafael, Sanjuán, Juan, Gallegos, María‐Trinidad
• Format: Article
• Language: English
• ISSN: 0950-382X; 1365-2958
• DOI: 10.1111/mmi.13278

In P seudomonas syringae pv. tomato DC 3000, the second messenger c‐di‐ GMP has been previously shown to stimulate pellicle formation and cellulose biosynthesis. A screen for genes involved in cellulose production under high c‐di‐ GMP intracellular levels led to the identification of insertions in two genes, wss B and wss E , belonging to the Pto DC 3000 cellulose biosynthesis operon wss ABCDEFGHI . Interestingly, beside cellulose‐deficient mutants, colonies with a rougher appearance than the wild type also arouse among the transposants. Those mutants carry insertions in amr Z , a gene encoding a transcriptional regulator in different P seudomonas . Here, we provide evidence that AmrZ is involved in the regulation of bacterial cellulose production at transcriptional level by binding to the promoter region of the wss ABCDEFGHI operon and repressing cellulose biosynthesis genes. Mutation of amr Z promotes wrinkly colony morphology, increased cellulose production and loss of motility in Pto DC 3000. AmrZ regulon includes putative c‐di‐ GMP metabolising proteins, like AdcA and MorA , which may also impact those phenotypes. Furthermore, an amr Z but not a cellulose‐deficient mutant turned out to be impaired in pathogenesis, indicating that AmrZ is a key regulator of Pto DC 3000 virulence probably by controlling bacterial processes other than cellulose production.